Nano-scale diamond (also referred to as “nanodiamond”) has a large number of excellent properties such as a high hardness and an extremely low coefficient of friction, and therefore, it has been already utilized in various fields and its development of application has been investigated as an extremely promising new material.
It has been known that nanodiamond can be synthesized by, for example, utilizing a detonation reaction of a high explosive. This synthesis method is generally called a detonation method, in which detonation is performed with only a raw material substance containing an aromatic compound having three or more nitro groups (hereinafter referred to as “low explosive raw material”) as a carbon source, and carbon atoms decomposed and liberated from a molecule constituting the low explosive raw material by the detonation reaction are formed as diamond at high temperature and high pressure during the detonation (for example, see Non-Patent Literature 1).
The production of nanodiamond by the detonation method has hitherto been performed in, for example, the East European countries such as Russia and the Ukraine, the United States of America, China, and the like. In these countries, since a military waste low explosive is inexpensively available as the low explosive raw material that is the carbon source, trinitrotoluene (TNT), an explosive mixture of TNT and hexogen (RDX: trimethylenetrinitramine) or octogen (HMX: cyclotetramethylenetetranitramine), or the like has been used.
In the present invention, a high explosive means a substance capable of performing a detonation reaction, and examples thereof may include not only a low explosive raw material but also a raw material substance containing an aromatic compound having two or less nitro groups (hereinafter referred to as “non-explosive raw material”). In addition, an explosive substance means a substance causing a sudden combustion reaction, and may be a solid one or a liquid one at normal temperature and normal pressure.
It is anticipated that the demanded amount of nanodiamond will increase more and more in the future with the development of its application.